The present invention relates to the percutaneous insertion of spinal fusion implants into the body of a patient and the affixation of those implants to the spine. In particular, the invention includes percutaneous posterior spinal fusion systems, devices used in conjunction with such systems, and associated methods.
Pedicle screw fixation constructs have been in use for decades in order to fuse adjacent vertebral segments to improve spinal stability or correct certain spinal deformities. Older approaches for inserting these fixation constructs involved open procedures, in which relatively large skin incisions were created to expose a substantial portion of the patient's spinal column, in order to allow for insertion of the pedicle screws and manipulation of spinal rods through openings adjacent to the heads of the screws.
Over time, less invasive approaches have been developed. Typically, in such approaches, pedicle screws are inserted into the pedicles of the same or adjacent vertebrae of a patient's spine through individual percutaneous incisions corresponding to the pedicle screws. Fixation or fusion rods are then inserted into the body through one of those incisions, or through an additional incision adjacent to the most cephalad or caudal pedicle screw, and the rod is rigidly connected to the pedicle screws such that the rod extends along the longitudinal axis of the spine (i.e., along the cephalad/caudal direction) in order to fix the relative positions of the adjacent vertebrae to which the rod is connected. In some such minimally invasive procedures, a device (e.g., a cannula, tower, or portal) is connected to each of the pedicle screws and extends through the respective percutaneous incision. Moreover, it is known to utilize separate elongate blades connected with the screws. Such devices provide a percutaneous passageway through the tissue from each incision to the respective pedicle screw, in order to aid in the insertion of a spinal rod. Examples of such passageway devices are described in commonly-assigned U.S. Pat. No. 7,955,355 (“the '355 Patent”) and U.S. Pat. No. 8,002,798 (“the '798 Patent”), the entireties of which are hereby incorporated by reference herein as if fully set forth herein.
Although considerable effort has been devoted in the art to optimization of such minimally invasive systems, still further improvement would be desirable.